1. Field of the Invention
The invention relates to a system for displaying images, and more particularly to an image display system comprising an organic electroluminescent display (OELD) device having an improved conductive path for signals and a fabrication method thereof.
2. Description of the Related Art
With the popularity of electronic devices, display system requirements accordingly increase. Organic electroluminescent displays (OELD) are widely used in electronic devices, for example mobile phones, car navigation systems (CNS), personal digital assistants (PDA) and camcorders, because of its advantages such as lower power consumption, relatively higher brightness and relatively rapid response time.
FIG. 1 is a cross-sectional view of a conventional organic electroluminescent display device. In FIG. 1, a substrate 2 having an array of thin film transistors (TFTs) 4 and a bonding pad 8 formed thereon is provided. Then, an anode electrode 6 and a pixel define layer (PDL) 10 is sequentially formed on the substrate 2 and the pixel define layer 10 covers the bonding pad 8. A contact hole 12, also referred to as a cathode contact hole, is formed to expose the bonding pad 8. A cathode electrode 14 is then formed on the substrate 2 and electrically connects to the exposed bonding pad 8 to transmit an exterior signal to the cathode electrode 14. Because the contact hole 12 has an extreme depth (namely thickness of the pixel define layer 10), the cathode electrode 14 formed on the sidewalls of the contact hole 12 is easily damaged, resulting in an inability to for the cathode electrode 14 to receive an exterior signal. A technique has been developed to avoid damage of the cathode electrode 14, where an indium tin oxide (ITO) layer serving as an auxiliary cathode (not shown) is formed on the cathode electrode 14. The indium tin oxide layer, however, has relatively higher resistance, resulting in relatively higher voltage drop and poorer display quality.
Thus, an organic electroluminescent display device and fabrication method thereof ameliorating the described problems is needed.